The present invention concerns a method for visually inspecting all kinds of tubular textile garments such as socks, sleeves, stockings, panties or the like, of the type comprising a first stage in which the article is loaded onto or unloaded from a support or stretcher, and a second stage in which said article is checked or inspected by means of a computer-aided vision system operating by means of an image acquisition stage and a final stage in which the acquired images are processed for thus detecting the flaws.
The devices of the above-mentioned type do generally comprise a contactless inspection based on a digital processing of images taken from different positions by means of a traveling motion executed with a mechanical system for positioning the system for the digital acquisition of said images.
As a background of the invention can be cited the report entitled xe2x80x9cInspeccixc3x3n visual de prendas a gran velocidadxe2x80x9d, published in the magazine Automxc3xa1tica e Instrumentacixc3x3n , October 1994, no. 47, pages 70-74, A. Llorens Castellxc3x3, A. Sanfeliu, J. J. Souto, describing a system for automatically inspecting panties for flaws, said system consisting of three main modules:
a mechanical module for automatically loading the garment onto a support and moving a lighting and camera assembly;
a circuitry module consisting of three circuit cards: a memory card with a 16 MB RAM with a line scan CCD camera input, an image preprocessing card whose core is comprised of the INP1000 systolic processor specially developed for the system, and a card for the visualization of the panty images, together with the corresponding software programs for access to the cards;
the image processing software programs implementing all the algorithms for processing said images and detecting the flaws for their ulterior rating.
The system operates as follows: The undyed panty is vertically mounted on a stretcher thus allowing to illuminate it and to acquire its image during the vertical travel of a line scan CCD camera of 1024 xe2x80x9cpixelsxe2x80x9d (picture elements) capturing the image line by line at right angles to the stretcher. The digititalized data are stored in the memory card, from where they are sent to the preprocessing card to be transmitted from there to a module for the extraction of characteristics and for their ulterior rating. Said stretcher has been provided to be shifted to place itself in front of the lighting and camera assembly, as well as to be turned such that the camera can thus when moving scan both sides of the garment.
The number and variety of the flaws to be controlled, and the frequency of the false alarms produced by seam shadows, overstressing of the fiber and other causes result in a very complex and costly image processing system.
One of the most significant problems inherent in the above-mentioned application derives from the need to correctly rate the flaws regardless of the type of material, garment size, finish and above all the tension to which the garment is subjected during the automatic mounting process, this entailing a high degree of parametrization of the algorithms implemented.
It is apparent that the described embodiment consists in a specialized machine, the system not being hence designed to be applied in textile or other machines already operating in the market.
The traveling motion of the lighting and camera assembly requires a space availability for said function requiring a predetermined free area.
The use of a line scan CCD camera (that scans the area to be inspected) involves long process times.
The lighting means employed by the described system comprise several fluorescent lamps strategically placed to obtain a correct illumination during the whole travel of the camera, this again imposing limitations when it comes to generalizing this application for its use with the standard machines that are commercially available in the market.
The object of the present invention consists in a method and system for visually inspecting tubular textile garments allowing to obviate the above-mentioned problems and to notably improve the efficiency of the system, and also allowing its implementation by means of a stationary image acquisition device of reduced dimensions.
The system being herein provided is essentially characterized in that it comprises a stationary camera and light source on an inspection area wherein the article to be checked is moved being kept under a predeterminated tension o a support or stretcher, and the method consists essentially in carrying out the inspection simultaneously with the introduction or egression of the finished article, tinted or not, onto or from a support such as a stretcher, with the essential particularity that said introduction of the article is carried out in the inspection area while being focused by said camera, uniformly illuminated and under a predetermined tension that is kept constant throughout the process. This results in said preset, constant tension giving the textile a uniform texture such that the distance between two filling or warp yarns is at all times smaller than a portion of any one of the flaws to be detected, which can thus be then correctly discriminated.
The stages of the method are detailed in claim 2 (20), and other particularities of the process appear in appended claims 3 (21) to 6 (24).
The essential characteristics of the system are on heir part detailed in claim 7 (25).
Other details of interest of the proposed system appear in appended claims 8 (26) to 18 (36).